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Topic: Mars Timekeeping System (Read 32440 times)

Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Minutes and seconds are as on Earth. Sols are Martian days, as already used. A mour is 1/24th of a sol. A meek is 7 sols. A marth is 30 or 31 sols. A mear is a Martian year. One of the marths will have 30 sols on some mears and 31 on other mears.

Mours, meeks, marths, and mears are so named to avoid confusion with the Earth versions but to be similar enough to make it easy to remember what each means.

Why? Well, sols are very useful because the day-night cycle is the most important regular time cycle to humans. A mour as 1/24th of a sol is so timezones work out right. Timezones have developed on Earth as a system that works pretty well. But does a mour need to be divided into exactly 60 of some unit? Not really. Minutes and seconds are often used to measure intervals of time, and there's good reason to keep these the same as on Earth. A 5 minute limit in a video game or a 20 minute timer for cooking would be the same as on Earth. It has the disadvantage that it's a little harder to figure out what time is 100 minutes from now, but then again that's not terribly simple for some people using Earth time, and not something that comes up all the time.

A meek as 7 sols is useful because over thousands of years, human civilization has adapted a cycle of 7 day-night cycles as a work-rest pattern. Why this instead of the 28 of a lunar cycle? Maybe it's just random, but I think there's a good chance it's because a cycle of 7 day-night cycles tends to work out fairly well for humans. Even if there's nothing inherently good about having a weekend every 7 day-night cycles, it's part of the culture of the first colonists and it will help them feel more at home. During the French Revolution, they tried to replace 7-day weeks with 10-day weeks as they were replacing other units with the metric units. The metric system was successful, 10-day weeks, not so much.

The marth is the one whose utility I'm least convinced of. But we have kept using months on Earth for 2,000 years after ithey became detached from the lunar cycle they started from. It might be because there's some utility in it. We don't really have much of our daily life revolving around months as we do with days and weeks, but it's a convenient way of partitioning the year into memorable chunks. We have images that come to mind when we think of August or February. It might be easier to think of what part of the year we're in when we have names for 30-or-so day-night cycle chunks than just using numbering within the year.

And the mear is a useful measure because it corresponds to the biggest climate cycle. Though I can also see the argument for the synod for as long as contact with Earth is important (i.e. a very long time).

In writing, instead of 8:04pm 11/4/2016, you'd have something like 22:04mt 11/4/2016md where the mt is Mars Time and md is Mars Date. That helps avoid confusion between Earth dates and times and Mars days and times.

People on Mars would also commonly use the Earth year for some purposes, I think. It's too deeply embedded in our culture. We think in terms of ages in years. And, for a long time, people will be aware of the current Earth date a lot of the time simply because they'll commonly be consuming media from Earth.

Lots of interesting points in this thread.1. Time zones present difficult complications for coordinating events planet wide on Mars, & are a historical construct colonists could leave behind.

2. Mars colonists will likely assign importance to time intervals not related to earth weeks or years. I agree with the synod observation, just as military enlistees may count the days to their release.

2A. Another possibly better analogy for guidance would be to look at how people stationed in Antarctica lend relevance to time. 24 hr daily cycles are important for biological reasons, but when it's 6 month long dark winter "night", they probably just count days & think about when it gets light again, & when do the re-supply planes start landing.

I think Mars timekeeping standards give a unique opportunity to correct some of the things we currently do wrong on Earth, due simply to historical accident.

My recommendations for 'corrections':

1) Get rid of AM/PM. 'Military' time only. The first hour is '0', not '12'.2) Make all months the same number of days (sols).3) Make each month an integral number of weeks. For Earth, this would best be done as 4 weeks per month, and switch to having 13 months. Leftover days (for Earth this would normally be 1 day, sometimes 2), would be placed at the end of the year after the last month and would just be 'Leap Days'. They would all be 'Sundays' (the last day of the week, see #6 below), i.e., they wouldn't advance the day of the week. Then the new year starts on Monday every year.4) Make each month start off at the start of a week. Taking numbers 3 and 4 together means we just don't need calendars anymore. The Nth day of the month, every month, forever, would be the same day of the week.5) Get rid of timezones. We'd all be better off if we just switched to UTC on Earth (Jim's objections notwithstanding). Oh, and without timezones, 'daylight savings time' makes no sense. Jettison it as well.6) While we're at it, make the first day of the week 'Monday', so those two days we call the 'weekend' are actually at the end of each week.

Mars Specifics:A) Keep a standard 'second'. The second is sacrosanct.B) Keep a minute defined to be 60 seconds, and an hour to be defined as 60 minutes.C) Have 'hour 24' consist of 39 minutes and 35 seconds. Then hour 0 starts. I slightly prefer this to Jim's solution of having hour 23 have an extra 39 minutes and 35 seconds.D) Retain a 7 day week (I think this is pretty culturally ingrained).E) So, to follow #s 3 and 4, above, we have to decide how many weeks per month, and the number of months. It looks like the best would be 5 weeks per month and 19 months. (This leaves I think 5, sometimes 6 'leap days' as defined above?)F) I'd suggest month names of Manuary, Mebuary, Arch, Mapril, Ay, Mune... Mecember, plus 7 more new month names.G) On the last 'leap day' each year, adjust for the built up leap seconds from rounding off the seconds of each sol.H) Manuary 1st (Day 0) of Year 0 will be defined to be the exact day a human first sets foot on Mars. (Unfortunately we are forever stuck with the mathematically confusing fact that we have no year 0 on Earth - we go from -1 to 1.)

Summary:

Keep the second, minute, hour and week as defined on Earth.

Let technology correct for the raggedy bits (extra partial hour each day, leap seconds at end of year) in an unobtrusive way.

Make several common sense improvements compared to present Earth systems.

I really hope we have just one time zone for the whole of Mars. It will make everything much simpler, and I know this from experience, having written software to organise meetings across different time zones.

I suggest, as have many others, keeping seconds , minutes and hours the same as on Earth. It would be fun to have Mars months of a combination of 30 and 31 Mars days, with new Mars relevant names. The year would begin on the shortest day of where the first human base is established, probably using the first human landing as year 0.

Lots of interesting points in this thread.1. Time zones present difficult complications for coordinating events planet wide on Mars, & are a historical construct colonists could leave behind.

I disagree. Timezones aren't "historical constructs". The reasons they were created are the same reasons we still use them and the same reasons people on Mars will use them.

They were created so that the same time labels all over the world apply to the same parts of the day. People can travel all over the world and know when it's noon, the sun will be approximately overhead. They'll know the sun will come up sometime around 6:00am and set sometime around 6:00pm. It's not always the same, but the best we can reasonably do while being able to easily keep track of what time it is for different people in different places and have nearby people using the same time as us.

Timezones are brilliant solutions to difficult problems. They are problems we have today just as much as we had them when they were developed. People shouldn't be so quick to dismiss them as relics of the past that aren't relevant in today's world.

2A. Another possibly better analogy for guidance would be to look at how people stationed in Antarctica lend relevance to time. 24 hr daily cycles are important for biological reasons, but when it's 6 month long dark winter "night", they probably just count days & think about when it gets light again, & when do the re-supply planes start landing.

I don't think Antarctica is a good analog for Mars as far as timekeeping goes. Mars has a light-dark cycle that is close to 24 hours. And it has a whole continuum of places where midday light is shifted by a constant factor from that in any given reference region. As far as timekeeping goes, most of Mars is much more like most of Earth than either is like the polar regions of either planet.

There are good reasons to have months that are different numbers of days. It allows you to have them come in the same place in every year without the lengths of the units being limited to factors of the number of days in a year.

3) Make each month an integral number of weeks. For Earth, this would best be done as 4 weeks per month, and switch to having 13 months. Leftover days (for Earth this would normally be 1 day, sometimes 2), would be placed at the end of the year after the last month and would just be 'Leap Days'. They would all be 'Sundays' (the last day of the week, see #6 below), i.e., they wouldn't advance the day of the week. Then the new year starts on Monday every year.

This just replaces one oddity with another one. I don't believe it's an improvement. Having some days that aren't in any month and some days that aren't in any week is a far more serious problem than having years and months begin on different days of the week, or months with small variations in length. It means, for example, that if you have something that you want done exactly once every 7 days, you can't just have it on the same day of the week indefinitely. It means you have to think carefully and do special calculations to see how many days away the Friday 8 weeks from today is. And there are many more issues.

4) Make each month start off at the start of a week. Taking numbers 3 and 4 together means we just don't need calendars anymore. The Nth day of the month, every month, forever, would be the same day of the week.

Oh, and without timezones, 'daylight savings time' makes no sense. Jettison it as well.6) While we're at it, make the first day of the week 'Monday', so those two days we call the 'weekend' are actually at the end of each week.

There's no commonly-agreed-on convention about which day of the week the week "begins" on. And there's really no need.

C) Have 'hour 24' consist of 39 minutes and 35 seconds. Then hour 0 starts. I slightly prefer this to Jim's solution of having hour 23 have an extra 39 minutes and 35 seconds.D) Retain a 7 day week (I think this is pretty culturally ingrained).E) So, to follow #s 3 and 4, above, we have to decide how many weeks per month, and the number of months. It looks like the best would be 5 weeks per month and 19 months. (This leaves I think 5, sometimes 6 'leap days' as defined above?)F) I'd suggest month names of Manuary, Mebuary, Arch, Mapril, Ay, Mune... Mecember, plus 7 more new month names.G) On the last 'leap day' each year, adjust for the built up leap seconds from rounding off the seconds of each sol.

That will cause more pain for computer systems than just putting the fractional seconds in the sols themselves. The more unevenness in the lengths of days, the worse it is. It's bad enough week get a leap second every once in a while, your scheme of saving them up and adding a bunch of them in one day would be much worse.

E) So, to follow #s 3 and 4, above, we have to decide how many weeks per month, and the number of months. It looks like the best would be 5 weeks per month and 19 months. (This leaves I think 5, sometimes 6 'leap days' as defined above?)F) I'd suggest month names of Manuary, Mebuary, Arch, Mapril, Ay, Mune... Mecember, plus 7 more new month names.G) On the last 'leap day' each year, adjust for the built up leap seconds from rounding off the seconds of each sol.

See how quickly you ended up with a convoluted hack?

For Mars, you'd be better off avoiding months entirely and just counting sols within the Martian year. Remembering 19 month names is no more useful than remembering that the early 400's is the start of winter, or that the 200's are dust-storm season and you have to prepare for occasional power rationing and generally schedule more guys for clean-up EVAs; or that you need to get low priority comms with Earth done by 340, 345 at the latest, because this year Earth is in solar-conjunction between 348-351 and comms is relay-only.

IMO, colonists will use the standard Julian Earth calendar for 90% of long term planning and time-tracking. I doubt there will ever be an elaborate and unique "Martian" dating system; likewise counting Martian Years as part of the date; likewise counting your age in Mars years. Years will be counted by the Earth standard, the current date is whatever it is on Earth. Not 33/17/247, the 33rd day of the 17th month, MarsYear 247, which is your 35th MarsBirthday and the year of your retirement...

Of course the date of Mars settlement will be an anniversary date, just like Independence Day in the US, or any "Founders Day" of any former colony on Earth. But the US doesn't have it's own calendar, it just occasionally celebrates big round numbers like the bicentenary. In 1976, not Year200US. There will not be a MarsYear 0.

Yes, they'll keep track of the part of day (or sol) they are in, for obvious local convenience, and I suspect they'll keep some track of the number of sols in the Martian year, and the synod. But that's it. There'll be no "Martian calendar" as such.

I get the nerd-appeal of creating calendars, I'm even a fan of the 13 month universal calendar, but it is neither necessary nor desirable on Mars.

I disagree. Timezones aren't "historical constructs". [...]They were created so that the same time labels all over the world apply to the same parts of the day.

For most of history there was no such thing as "time zones", the time was always based on immediate solar time. Ten miles down the road, the time would be slightly different. Every village had their own time. The combination of better clocks and increased speed of transport meant that coordinating between regions became harder, so regional time was created. (Historically, train timetables played a big role in that. Communities would gradually adopted nearby train-time as their local time, even if it was 10-30 minutes away from true solar time. According to wiki, Great Western was the first railway company to create a uniform time zone within their network.)

That led to "time zones" in different countries and regions within countries. But not the current nearest-hour system. Local time zones were still based on some previous local point, so neighbouring countries might be something random, like 47 minutes apart. The push to make it more uniform didn't really start until 1900 and took 30 years. (We still haven't truly adopted the uniform time-zone system. You just need to look at a map of actual time zones. It's a horrible mess.)

Historically, the local day could start at sunrise, sunset, noon or midnight, depending on local custom. Solar zenith, noon, could be the seventh hour, the first, or the twelfth. (You see the remnants of this in many religious customs, where a holy day goes from sunset on one day to sunset on the next.)

Midnight doesn't have to be the start of the local day, "12" doesn't have to be when the sun is at local zenith (give or take). People have adopted a wide variety of systems and coped perfectly well.

As I said earlier, for decades after permanent settlement begins, the local time of the first colony site will be the most important "clock" to keep track of. (And for a long time, even that will run second to Earth's UTC.) Research and supply stations scattered at significant distances will still use "Colony Time", just as the US military uses UTC, and for the same reasons. And IMO, by the time there are major secondary settlements more than a few hundred kilometres away from the first colony, that single universal Colony Time will be so entrenched that the idea of introducing different time-zones will seem bizarre. The negatives will be seen as outweighing any possible convenience of a separate clock based on local-noon.

It's different on Earth. Adapting to a single global time would be chaos, we can't even finish the change to the existing time-zones. But on Mars, they'll start with universal planetary time. Introducing time zones would be the thing that causes confusion and is resisted.

Historically, the local day could start at sunrise, sunset, noon or midnight, depending on local custom. Solar zenith, noon, could be the seventh hour, the first, or the twelfth. (You see the remnants of this in many religious customs, where a holy day goes from sunset on one day to sunset on the next.)

3 pages into this thread, I think the first interplanetary war will start when the Imperial Martian ambassador to Earth misses his meeting with United Nations Proconsul to the Main Belt mining colonies. All because he didn't compensate his mars time zone clock at His Olympus Mons chateau with against the clock of the main colony at Hellas Basin.

It seems like if we want to keep the second unmodified (a necessity IMHO) AND have timezones that make sense, you have to either modify the number of seconds in a minute or the number of minutes in an hour.

My thought is a minute should be defined as 59 seconds. (Alternatively you could define an hour as 59 minutes.) Then there would be 25 hours a day of 60 minutes each, all minutes and seconds would match up at all times in all timezones, and the second doesn't need to be changed.

If I've calculated it correctly, that's only about a second off each day from an exact sol. Perhaps midnight at the Mars equivalent of GMT once a year there could be a few minutes of adjustment to bring the clock back in line with the sun.

It seems like if we want to keep the second unmodified (a necessity IMHO) AND have timezones that make sense, you have to either modify the number of seconds in a minute or the number of minutes in an hour.

Or create new units that perform the same function. We already have sols instead of days, so instead of hours, minutes and seconds, have ores, lepta and defterolepta (those are greek equivalents - I think - but you could have something else!). Granted, you then have two units for the same thing, but those of us in the UK or US and elsewhere are used to this. I can quite happily deal in meters and yards, miles and kilometers, pounds and kilograms, pints and liters and acres and hectares. Which I use depends on the context - liters to buy milk from the supermarket, pints to buy beer in my local! So, for daily life on Mars, you'll probably use ores and lepta (or whatever) and for science and engineering, the second and other SI units.

People aren't going to use the 24-hour clock like the military. We could do that now, and often do for train times etc. But we don't. People prefer to keep the am/pm distinction. So, unless you're going to criminalise people on Mars for answering six instead of 18 to 'what's the time?', I expect it will continue. And people will want a whole, preferably even number of time units in a sol. Who wants to do complex mental arithmetic to work out what half a day is?

Just use decimal fractions of sols. Half way through the day is 0.5. Each thousandth is nearly 90 seconds, each hundredth is nearly 15 minutes, each tenth almost 2.5hrs, so quick'n'dirty conversion isn't difficult.

I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...

https://en.wikipedia.org/wiki/International_Fixed_Calendar"The several advantages of The International Fixed Calendar are mainly related to its organization.- Every year has exactly 52 weeks divided in 13 months.- Each month has exactly 28 days divided in 4 weeks.- The calendar is the same every year (perennial), unlike the annual Gregorian calendar, which differs from year to year. Hence, scheduling is easier for institutions and industries with extended production cycles.- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."